The present invention relates generally to a copying apparatus comprising a tracer for tracing automatically a contour of a pattern to be traced and a working machine having a working head movable in conjunction with the tracer with a given relationship for effecting a given working operation for an object. More particularly, the present invention relates to a method for controlling an operation of the copying apparatus and an apparatus for carrying out the method.
As an example of such a copying apparatus a copy-gas cutting apparatus has been known, which comprises a tracer for tracing automatically a contour of a pattern described on a template and a gas torch assembly having at least one blowpipe for jetting a cutting oxygen flow against an object such as a steel plate. In operation the steel plate is cut by the oxygen flow from the torch, while the tracer follows the pattern on the template in a mechanically contacting or photoelectrically non-contacting manner. In this manner an article or workpiece having the same shape as the pattern of template can be automatically cut out of the steel plate.
In the case of working the object, i.e. the steel plate with such a copy gas-cutting apparatus, the tracer is at first positioned manually at a point which is slightly remote from the pattern on the template and the gas torch assembly is operated to form a hole in the steel plate. This operation is sometimes referred to as piercing. Then the tracer is manually moved from the piercing point to a copy start point on the pattern, while the oxygen gas flow is ejected from the torch, i.e. the cutting operation is continued. After that the tracer traces automatically the pattern on the template and the steel plate is cut accordingly. When the tracer reaches a tracing end point, the ejection of cutting oxygen flow is stopped and then the tracer is removed from the template. In the known copying apparatus an operator must stay always besides the apparatus to control manually the movement of the tracer and the operation of the gas torch. Therefore the known operation is very cumbersome and working efficiency is very low. Particularly in case of effecting a series of operations with using a single template, the operator has to move the tracer to a piercing point each time the single operation has finished. Such operation is much more cumbersome.
In order to obviate the above mentioned drawback there has been devised a copying apparatus in which a tracer moves automatically from a piercing point to a copy start point on a pattern and from a copy end point on the pattern to a next piercing point for a next pattern along guide lines described on the template. In this case it is necessary to prepare special templates on which guide lines have been previously described and thus ordinary templates which have been used heretofore could not be utilized. Since the template requires a very high accuracy the upmost care should be taken in manufacturing the same. Therefore its manufacturing process is quite complicated and results in high cost. Further in actual operation it is sometimes undesirable to predetermine the piercing points, start points and end points in accordance with the shape and material of objects to be worked, shape of pattern, arrangement of patterns in case of using a plurality of patterns. In such a case the template having the guide lines previously described thereon could not be used and the operator must move the tracer manually or a new template having a new guide line described thereon has to be prepared. In either cases the working efficiency becomes lower to a great extent.
Further there has been developed a so-called numerical control system in which position of the working machine with respect to the object are previously set as numerical values which are then stored in a memory as a given program. The movement and operation of the working machine are controlled in accordance with the numerical data read out of the memory. It is apparent that such a numerical control system is very complicated in construction and expensive. Moreover the operation of the machine is exclusively controlled in accordance with the previously determined program and thus could not be easily changed upon the actual working and lacks flexibility. In other words the piercing points, start and end points of copying, etc. could not be simply changed in accordance with the shape and material of object, the shape of the pattern and arrangement of patterns. In practice, the numerical control system is quite inconvenient for effecting particular operations.
Upon operating the known copying apparatus the operator has to control or command the operation of the working machine as well as the movement of the working machine into given positions. For instance, in the copy gas-cutting machine after the tracer has been moved into a piercing point the gas torch is rendered operative to produce a jet of cutting oxygen flow by operating a suitable member on a control panel. When the tracer has reached a copy end point, the oxygen flow is stopped and the tracer is moved into a next piercing point. Then the cutting oxygen gas flow is again jetted from the gas torch. The above mentioned operation is rather cumbersome and results in a decrease in operation efficiency. In the numerical control system these operational functions of the working machine can be previously stored in a memory, and during the working, the operational function of working machine can be controlled by reading the command signals out of the store. However as described above, the numerical control system is very complicated and expensive and lacks the flexibility.
In U.S. Pat. No 4,328,050, there has been proposed a method of controlling a copying apparatus, in which prior to an actual working operation, a tracer is manually moved with respect to a pattern to detects coordinates of the tracer at piercing points, copy start points, copy end points, etc. and the coordinates thus detected are stored in a memory, and during the actual working operation, the movement of a working head out of the pattern is controlled by the stored coordinates and the movement of the working head on the pattern is controlled by the movement of the tracer following the pattern. By means of such a control method, use may be made of ordinary templates without guide line and further various operational points such as piercing points and copy start and end points can be freely determined at the actual working and thus the large versatility and flexibility can be obtained. However, in this control method, every time the template is changed, coordinates of operational points must be stored in a memory and therefore, the total efficiency of the copying machine could not be sufficiently high.